1. Field of the Invention
The present invention relates to a chucking mechanism operable to detachably set thereon a discoid disk, and to a motor including the chucking mechanism, and a disk driving apparatus including the motor.
2. Description of Related Art
In recent years, a slot loading mechanism in which a disk is slid in and out of a disk driving apparatus is used in a personal computer (hereinafter, referred to as PC). This mechanism is particularly useful for a PC having a slim shape.
The slot loading mechanism requires no tray moving the disk to a spindle motor which rotates the disk, and therefore is allowed to be slim. However, there is an increased demand to further slim down the disk driving apparatus. In order to further slim down the disk driving apparatus, the spindle motor used therein also needs to be slimmer. It is, however, a difficult task to reduce a thickness of a chucking mechanism on which the disk is removably set and which is arranged in the spindle motor.
Also, the disk driving apparatus having applied thereon the slot loading mechanism usually retains the disk by itself without using a clamping member in order to achieve a thin chucking mechanism.
FIG. 14 is a diagram showing a cross sectional view, in an axial direction, of a conventional configuration of the chucking mechanism.
According to FIG. 14, a chucking mechanism 1 includes a turn table 2 having a disk setting surface 2a on which a disk (not shown in FIG. 14) having a central opening portion, a center case 3, a plurality of claw members 4, and a coil spring 5 which is an elastic member providing a radial force for each claw member 4. The center case 3 includes a cylindrical portion 3a around which an inner circumferential surface of the central opening portion of the disk will be arranged, a top plate portion 3b arranged such as to cover a top end of the cylindrical portion 3a, and a plurality of openings 3c allowing the claw members 4 to move therethrough. The claw member 4 includes a disk retaining surface 4a which makes contact with the central opening portion so as to retain the disk, and a sliding surface 4b which guides movements of the claw member 4. Also, the center case 3 preferably includes an upward guiding surface 3d which makes contact with the claw member 4 so as to guide a sliding movement of the claw member 4. Also, the claw member 4 includes at an inner circumferential surface thereof a protrusion 4c which makes contact with the coil spring 5.
Next, a movement of the claw member 4 in an axially downward direction when a disk 6 is set on the chucking mechanism 1 will be described with reference to FIGS. 15 and 16. FIG. 15 is a cross sectional view of the conventional chucking mechanism 1 when the disk 6 begins to make contact with the claw member 4. FIG. 16 is a cross sectional view of the conventional chucking mechanism 1 in which a tip portion of the claw member 4 is at an axially lowest position. Hereinafter, the disk 6 is a multilayered disk including an upper disk base 6b and a lower disk base 6c pasted to one another.
According to FIG. 15, the claw member 4 makes contact at a top surface thereof with a bottom end of the central opening portion 6a of the disk 6, the lower side surface of the disk retaining surface 4a slides with the upper guiding surface 3d, and then the tip portion 4b of the claw portion 4 moves in the axially downward direction while an entire claw member 4 moves in a radially inward direction.